The complexes of carcinogens (e.g., benzo(a)pyrene, 4-nitro-quinoline-1-oxide, and acetoxy-acetylaminofluorene) with high molecular weight native DNA, plasmid DNA; synthetic DNAs, and deoxyoligonucleotides will be studied. The experiments will include Nuclear Magnetic Resonance (NMR), fluorescence, circular dichroism, and UV-Vis spectroscopic studies on the complexes of carcinogens with DNA and oligonucleotides. Of particular interest will be the structure of the complexes as well as the site-selectivity and cooperativity in the covalent binding of the carcinogens to DNA.